Many receivers use Low Noise Amplifiers (LNA) to enhance receive signal levels prior to further signal processing. For example, an LNA may be coupled to a receive antenna with potential filter circuitry in between. The LNA at an input of Radio Frequency (RF) receivers may be considered essential for any modern transceiver with challenging sensitivity requirements. Fully differential LNAs (outputting differential signals, basically two signals with opposite polarity) may be used because they can be connected with a double balance mixer which inherently possesses lower second order nonlinearity than single balance mixers, and may also effectively suppress any kind of common mode noise sourcing from supply or ground.
Because of the increasing amount of RF input ports in a transceiver, most multi-mode and multi-band transceivers use single-ended LNAs with single ended outputs potentially saving input balls and chip area. Therefore, single balance mixers are utilized which increases the second order nonlinearity of mixers and causing, at least in some cases, a complex mixer calibration, further utilization of bulky and large blocking capacitors for supplies noises, respectively.